【题目】There was a time ______ I thought my dad didn't know a thing about being a good father.
A.when
B.which
C.that
D.what

【答案】A
【解析】考查定语从句。句意：曾经有一段时期，我认为我的爸爸根本不知道如何做一个好父亲。a time是先行词，在when引导的定语从句当中做状语，故选A。